CASP Checklists

This set of eight critical appraisal tools are designed to be used when reading research, these include tools for Systematic Reviews, Randomised Controlled Trials, Cohort Studies, Case Control Studies, Economic Evaluations, Diagnostic Studies, Qualitative studies and Clinical Prediction Rule.

Some Study Designs…..

What is a Systematic Review?

Frequently there will have been more than one study addressing a particular health question. In such circumstances it is logical to collect all these studies together and base conclusions on the cumulated results. However the same scientific principles as would be expected in the original studies need to be applied to the identification, sorting and analysis of potentially relevant studies. This is what is meant by a systematic review. The most obvious sign that a review is systematic will be the presence of a methods section. Meta-analysis is the statistical process of combining the results from several studies that is often part of a systematic review.

What is a Randomised Controlled Trial (RCT)?

An RCT is a type of interventional or experimental study design. Participants (individuals or groups) are randomly allocated to receive either the new intervention being tested or a control treatment (usually the standard treatment or a placebo). Each arm of the study is then followed up and the amount or severity of the disease measured in the intervention group and compared with the control group. RCTs are by definition prospective.

What is a Qualitative study?

A qualitative study examines the experiences and beliefs of people from their own perspective. It can take many forms including in-depth interviews and focus-groups with analysis attempting to identify underlying themes. Verbatim quotes of participants can be used to illustrate these themes.

What is a Cohort study?

A cohort study, also known as a follow-up or longitudinal study, is another observational study design. In this study a population who do not have the health outcome or disease of interest are first divided into those who are exposed to a risk factor and those who are not. Alternatively exposed and unexposed populations may be chosen separately. Irrespective, both groups are then followed, often over long periods of time. At the end of the period of observation the incidence of disease or frequency of health outcome in the exposed group is compared to that in the unexposed group. The study is generally prospective as it looks forward from potential cause to consequence.

What is a Case-Control study?

A case-control study belongs to the observational group of studies. It begins by choosing individuals who have a health outcome or disease whose cause you want to investigate. These are the cases. Controls without the health outcome are then chosen. You then determine the proportion of cases who were exposed to any risk factor of interest in the past, and compare this with the proportion exposed in the control group. The study is generally retrospective because it looks backwards in time to the earlier exposures of individuals.